1. Field of the Invention
The present invention relates to a roll winding device and method, and more particularly to a device and method using two carrying rollers which form a winding bed for receiving a wound roll.
2. Discussion of Background Information
A known roll winding device is discussed in German Patent Document No. DE 195 24 905 A1.
In one of the last production steps of producing paper webs, paper webs are usually cut to a desired width and then wound into rolls before they are packaged and shipped. The winding cores onto which the paper rolls are wound have a relatively low stiffness and carrying capacity, in contrast to the drums used during paper production. These cores are often cardboard tubes. As a result, paper rolls usually have to be supported by supporting rollers during the winding process. This is especially pronounced when the winding device is a carrying roller winder. In such a configuration, the roll rests on carrying rollers without any additional supporting devices acting on the core. But even in a supporting roll winder, where additional supporting devices act on the roll core, support is provided by a roller.
When the paper rolls become larger and thus heavier, the support line forces of the paper roll on the support roller or rollers become relatively large which has the disadvantage of causing winding hardness to increase. This winding hardness often causes the roll to split open later. To reduce the burden on the rolls and to reduce the line forces, pneumatic overpressure can be produced under the roll so that the roll is at least partially resting on an air cushion.
This measure is generally effective. However, a relatively large amount of air is needed to lessen the weight burden on the roll. With roll widths that change often, a relatively large amount of air escapes at the end regions. It is possible to reduce this loss of air by axially dividing the pressure chamber (i.e., parallel to the carrying rollers), into several sections and only providing air to the sections that are completely covered by the wound roll. However, this arrangement often leads to insufficient support from pressurized air in the edge regions of the wound roll. Also, if pressurized air is also provided to the areas that are not completely covered by the wound roll, a considerable loss of air will still occur.